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By Terry McMahon, Steve Walton and Jim Tatera
Analytical instruments used for online chemical analysis of process streams or plant environments are generally called process analyzers. On-stream analytical data have proven to be crucial to safe and efficient operation in the petroleum, chemical, pharmaceutical, pulp and paper, power and other industries. Historically speaking, these instruments have been complex, even temperamental, systems with relatively unique operational and maintenance needs. If online instrumentation, sample-handling systems and data-analysis software are to realize optimum performance, they will require continual attention from the analyzer support staff.
Increasingly, however, regulatory and high-priority economic concerns such as operator health and safety, emissions control and energy conservation are raising the importance of analyzer reliability to normal operations. Particularly with respect to regulatory and safety uses, the time logged as out-of-limits because of an analyzer outage can result in stiff fines.
In these situations, it’s important to be able to deal with routine maintenance needs, as well as to recognize and characterize maintenance needs that require more specialized skills. Sourcing such specialized skills and an expedited response to an incident frequently become high-priority items.
A brief overview of analyzer history can put the current situation into perspective. The technology for on-stream chemical analysis dates back about 70 years. The first nondispersive infrared (NDIR) photometers were developed and deployed in the late 1930s at the Ludwigshafen Research Lab of I.G. Farbenindustrie (German Chemical Trust later broken up by the Allied Occupation Forces into BASF, Bayer and Hoechst). A schematic of UltraRotAbsorptionSchreiber (URAS), the first on-stream analyzer, is shown in Figure 1. The URAS trade name belongs to the original manufacturer, Hartmann & Braun, which is now a unit of ABB, a leading worldwide analyzer supplier. When this work was discovered, its significance was recognized immediately (British Intelligence Operations Subcommittee Report #1007, 12 June 1946). The report states that “I.G. Farbenindustrie’s development in recent years of the infrared absorption meter and the magnetic oxygen recorder represent a great advance.”
Figure 1. This block diagram shows the major components
U.S. chemical and petroleum companies began using on-stream analyzers in the 1950s. By 1960, Standard Oil of New Jersey’s (later Exxon) Baton Rouge Refinery had a significant complement of on-stream analyzers (Table 1).
|Analyzer||Installed Cost ($M)||Suppliers|
|Gas chromatograph||10 to 15||Beckman, Consolidated Electrodynamics, Greenbrier, Perkin Elmer|
|Densitometer||8||Precision Thermometer & Instrument
|Final boiling point
||9||Hallikainen, Precision Scientific, Technical Oil Tool Co. (TOTCO)|
|Flash point||10||Precision Scientific|
|Hydrogen sulfide (Pb acet tape)||11||Minneapolis Honeywell Rubicon|
|Ionization chamber (ppb gases)||10||Mine Safety Appliances
|Initial boiling point||5 to 8||Hallikainen, TOTCO|
|Infrared (NDIR)||8 to 12||Beckman, Liston-Becker, Mine Safety Appliances|
||7||Beckman, Consolidated Electrodynamics, Mfrs Engineering and Equipment|
|Moisture (heat of adsorption)
||14||Mine Safety Appliances|
|Differential refractometer||6 to 12||Consolidated Electrodynamics, Greenbrier|
|Reid vapor pressure (RVP)
|Ultraviolet||10||Analytic Systems Co.|
The emergence of real-time digital computers in the 1960s, followed by the microelectronics revolution and the large-scale integration microprocessor in the 1970s, eventually allowed exploitation of highly sophisticated analytical techniques for on-line analysis. These developments required several decades to develop. During the past 10 years or so, the full power of on-stream chemical analysis, combined with modern information technology, has taken hold throughout the process industries and is generating higher productivities, yields, efficiencies and product quality.
Realizing these benefits required highly skilled and experienced technical personnel. The analyzer community evolved into a culture suited to the care and tending of these useful industrial analyzer tools. The question facing plant operations management is: How do you realize the enormous potential benefits of on-stream analysis without the overhead of on-site analyzer specialists?
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